This invention relates to radiopharmaceuticals and more particularly to such materials suited for use in treatment of calcific tumors; i.e., primary and metastatic bone tumors and soft tissue calcifying tumors.
Radiation therapy for tumors of various types has been well known for some time. One of the main difficulties with all radiation therapy is the lack of specificity of both externally applied radiation and radioactive materials; i.e., the radiation therefrom is generalized and has a substantial effect on bone marrow activity and soft tissue which is not tumerous as well as that which is.
Attempts have been made heretofore to provide site selective radiopharmaceuticals with some success. For example Storaasli reported in the Journal of the American Medical Association 210, 1077-1078 (1969) that sodium phosphate having incorporated therein the radioactive isotope of phosphorus having an atomic weight of 32 (.sup.32 P) had a measure of selectivity for osseous tumors. The selectivity achieved by this approach is apparently related to the high uptake of phosphorus in tumors as reported by Anghileri in Experientia 28 Number 9, 1086-7 (1972) but is insufficient to allow an effective dose of radioactivity to be directed to a bone tumor without simultaneously directing a damaging dose to unaffected bone, bone marrow and other soft tissue cells. Consequently radioactive phosphates (and polyphosphates) have been restricted to use in extreme or terminal bone tumor cases where the high risks of additional damage were warranted.
Prior to the present invention, no compound or method existed whereby effective therapeutic or pain relieving doses of radiation could be directed to bone tumor sites without a substantial risk of radiation damage to the remainder of the body.
Accordingly, it is the object of this invention to provide a means for introducing quantities of radiation sufficient to reduce pain and/or have a therapeutic effect on primary or metastatic tumors without simultaneously damaging non-tumorous bone, bone marrow and soft tissue and cells.